-12- 



Figure 10. Bark on three year-old wood from Delicious trees showing measles (top 

 of photograph) as compared to normal bark (bottom of photograph). 



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POMOLOGICAL PARAGRAPH 



William J. Lord 

 Department of Plant and Soil Sciences 



New Apple Rootstock Will Soon Be Available. Mark a new size-controlling rootstock, 

 one of a series of rootstocks developed by Dr. Robert Carlson, Michigan State University, 

 Professor emeritus of Horticulture, will soon be commercially available. Trees on 

 Mark (formerly designated MAC-9) are reported to be well-anchored, precocious and 

 between M9 and M26 in size. Thus, Mark under Michigan conditions, shows great promise 

 as a size-controlling rootstock that enhances early fruit production and requires no 

 support because of poor anchorage or brittle roots. 



We have Starkspur Supreme Delicious on Mark at our Horticultural Research Station 

 in Belchertown but the trees are only 4 years old. Nevertheless, the trees on Mark 

 presently appear to be well anchored, precocious and somewhat larger than those on 

 M26. In contrast, unsupported Starkspur Supreme Delicious trees on M9 or EMLA27 

 are leaning badly or have broke at the scion-rootstock union. 



It is reported that limited quantities of trees on Mark will be available for purchase 

 during the winter of 19 86-87. By this time Mark will have been more thoroughly tested 

 because it has been included in the North Central Region Cooperative Rootstock Trial 

 established in 1980-81 at 25 locations in the United States and 2 in Canada. 



